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Determination of Lattice Parameters of Polytypes in Liquid‐Phase‐Sintered SiC Using the Rietveld Method
Author(s) -
HernándezJiménez Angel,
Ortiz Angel L.,
SánchezBajo Florentino,
Guiberteau Fernando,
Cumbrera Francisco L.
Publication year - 2004
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2004.00943.x
Subject(s) - rietveld refinement , crystallite , materials science , lattice constant , lattice (music) , phase (matter) , sintering , ceramic , crystallography , crystal structure , optics , diffraction , composite material , chemistry , physics , metallurgy , organic chemistry , acoustics
Accurate determination of lattice parameters of polytypes in liquid‐phase‐sintered (LPS) SiC by conventional X‐ray powder diffractometry is difficult due to the severe overlap between different Bragg reflections and to the presence of geometrical aberrations. For this reason, results obtained by traditional internal‐standard d ‐spacing methods will be in general unrealistic. In this context, the Rietveld method, which is based on the refinement of a structural, profile, and instrumental model, is a more appropriate procedure to determine lattice constants of polytypes in these ceramics. Therefore, in this study we evaluated the accuracy of the results given by the Rietveld method for multiphase mixtures of SiC polytypes, when line broadening is dominated by the crystallite size. The accuracy was found to be remarkable, being sensitive to the number of polytypes but insensitive to the length of the lattice parameters and to the number of geometrical aberrations. In addition, an application to an LPS SiC specimen revealed the usefulness of the Rietveld method to better understand the microstructural evolution during sintering.